Preliminary Study of a Single Instillation of Low-Concentration High-Volume Silver Nitrate Solution for Chyluria: Is >10 mL Instillation an Absolute Contraindication in the Real World?

Silver nitrate instillation (SNI) is one form of treatment for chyluria. However, there is the opinion that a high volume of SNI (>10 mL) should be avoided because life-threatening complications have been reported. However, we have noticed that most severe complications occur in high-concentration treatments (≥1%), even with a small volume. In addition, a small volume (≤10 mL) of low-concentration (<1%) SNI occasionally causes recurrence. Based on these facts, we aimed to evaluate a preliminary study of a novel single-injection regimen of low-concentration high-volume SNI. In this preliminary study, nine patients who underwent SNI were retrospectively examined. Patient characteristics, anesthesia, procedure, efficacy, complications, and duration of hospital stay were investigated. The volume of silver nitrate solution was decided based on symptoms, findings of pyelography, and vital signs, and it was given as a single instillation. This study was approved by the Institutional Review Board. The ranges of silver nitrate concentration and volume were 0.1%–0.5% and 15–30 mL, respectively. In all patients, proteinuria and cloudy urine disappeared immediately. However, two patients had recurrence after the initial SNI. These two patients were subsequently treated with increasing concentrations of silver nitrate (0.2% and 0.5%) from 0.1%, and they had complete symptomatic relief without recurrence for more than 6 years. None of the patients experienced severe complications. In conclusion, our preliminary study showed that a single instillation of low-concentration (0.1%–0.5%) and high-volume (15–30 mL) SNI is safe and useful. It is worth considering as a treatment option for chyluria.